A long while back (in a galaxy very far away), we built a temp and humidity monitor with the SHT-21 chip. It's a very accurate, albeit very expensive, solution. What if good enough, is good enough? If you don't need scientific resolution, the DHT-11 is a very inexpensive solution. Today we built a temp and humidity monitor with this module. I started off with a DHT-11 breakout board from geeetech. I used this module because it has the pull up resistor and a conditioning capacitor onboard. I connected S (signal) to pin 2, - to Gnd, and + to 5vdc.